Wireless data networks allow mobile devices to be remotely connected to services such as email distribution and internet browsing without connection to a conventional computer interface. Many publicly accessible data networks that can function over a wide area rely upon a cellular infrastructure and are tied to cellular protocols such as IS-95 which describes Code Division Multiple Access (CDMA) cellular communications, and the Global System for Mobile communications (GSM). Each cellular protocol has a companion data protocol. For GSM communications General Packet Radio Service (GPRS) is the packet data companion protocol, for IS-95 networks the “One Times Radio Transmission Technology” standard (1XRTT) defined in the CDMA2000 specification is the companion data protocol.
1XRTT provides CDMA2000 air interface devices with a packet based radio service that is capable of high data transmission rates, and supports both simple IP and mobile IP data connections. One disadvantage of the 1XRTT system is that network resources such as IP address are consumed simply maintaining a series of otherwise inactive connections. This is problematic for many carriers as resources such as the IP address space are finite and cannot be extended. As a result, carriers commonly drop inactive data connections when networks become congested to release occupied resources. Additionally, carriers often drop connections that have not been active for a fixed period of time regardless of network usage levels, so that resources are not allocated to inactive connections. A device that has been disconnected from the network due to inactivity typically releases its assigned network resources and only reconnects when the user of the mobile device attempts to access data services.
If a connection is terminated, the resources allocated to the mobile device are released. Thus upon reconnecting to the network, the mobile device is reassigned resources, which it typically then registers with a number of services. However, between the time the resources are released and the time at which the reacquired resources are registered, the device is not available for service. This is problematic for push enabled “always-on” devices since connections are important for bi-directional communications, which involve data transfers that are not initiated by the mobile device. If the wireless data connection is being used to push data from a remote server to a mobile device, the mobile device must remain connected, as a remote server cannot connect to a mobile device that the network has disconnected. Such a device requires an “always-on” 1XRTT data connection that is capable of automatically recovering from a disconnection.
Another problem presented by present 1XRTT devices occurs when a data connection cannot be immediately obtained. This can occur both at the time at which the device is initialized, and at the time that the device attempts to reacquire a connection. Typically the device will either continuously poll the network for a connection, or it will make a fixed number of connection attempts before it determines that a connection cannot be obtained at which time it will seek user interaction. The first method is counterproductive as it increases network traffic, which reduces the capacity for data channels. As a result, many networks prohibit continuous polling. A method of varying the length of time between connection attempts is disclosed in International Publication No. 01/474112 to Denso Corporation. However, if the device experiences difficulty connecting and maintaining a connection to the wireless data network, seeking user interaction merely notifies the user of the lack of connection, and does not assist in reacquiring the connection.
It is, therefore, desirable to provide a mobile device for connecting to a 1XRTT data network that is capable of maintaining an “always-on” data connection with automatic disconnect recovery to minimise the amount of time that a data connection is not available.